Acupuncture may cut a woman's chances of a woman having a baby through IVF, doctors have warned.

Research showed that women who combined the ancient Chinese art with modern fertility treatments were almost 40 per cent less likely to become pregnant than those who used IVF alone.

The finding suggests that women who turn to acupuncture to boost their chances of motherhood may be wasting both their time and money.

Previous studies have provided conflicting evidence about the value of acupuncture in helping IVF, with some finding it doubles the chances of pregnancy and others finding it more of a hindrance than a help.

Supporters of the technique claim it boosts fertility by increasing blood flow to the womb and helping balance the hormones critical for conception. It may also boost both the production of eggs and their quality.

Acupuncture can also relieve stress, while some believe women benefit from the extra fuss and attention surrounding the treatment.

Gordon Brown's wife Sarah is said to have used acupuncture to help her conceive, while other devotees of the 3,000-year-old technique include Cherie Blair and actress Gwyneth Paltrow.

In the latest study, the US researchers looked at the effect of acupuncture on just over 100 women undergoing fertility treatment.

Half of the women underwent 25-minute sessions of acupuncture immediately before and after IVF, while the others simply had IVF.

Just 44 per cent of the women in the acupuncture group became pregnant - compared with almost 70 per cent in the other group, the American Society for Reproductive Medicine's (MUST CREDIT) annual conference heard.

It is unclear why acupuncture actually hampered the women's chances of pregnancy.

In the past, it has been suggested that women resort to acupuncture when all else has failed, suggesting they may have greater infertility problems than other women.

However, this could not apply in this case as the women were randomly assigned to either the acupuncture group or the other group.

Researcher Dr LaTasha (CORR) Craig, a fertility expert at the University of Oklahoma, said: "The results of our study suggest women having fertility treatment should not be advised to have acupuncture.

"This contradicts the findings of previous studies. I think more research needs to be done."

Mark Bovey (CORR), of the British Acupuncture Council, said the US finding seemed to 'fly in the face' of other research.

He added: "Some practitioners treat hundreds of women having IVF each year and largely have good results with it."